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Editor's Note: This article was originally published on January 11, 2001. However, the
original title was misleading and has been modified to increase clarity.
There has been much debate in recent
years about the benefits and risks of taking hormone replacement
therapy (HRT). Now, researchers from the American Cancer Society have published the
results of a large study of post-menopausal women that may help clarify some of the
effects of HRT on heart disease and cancer. According to lead researcher Carmen Rodriguez, MD
and her colleagues, estrogen therapy may help reduce the number of deaths from cancer and
offers protection against heart disease for thin women (see below).
Before menopause, the female body produces the
hormones estrogen and progesterone in the ovaries. When a women reaches menopause, her
estrogen and progesterone levels are reduced, and she may experience hot flashes, vaginal
dryness, sleep disturbances, or other symptoms. HRT is designed to replace the hormones
lost at menopause. HRT regimens contain estrogen, progestin (a synthetic form of
progesterone), or a combination of the two. Most physicians recommend that women take a
combination of estrogen or progestin because taking estrogen alone may increase the risk
of endometrial cancer (cancer of the uterine lining). Previous
studies have shown that HRT reduce the risk of heart disease by lowering cholesterol.
In the American Cancer Society study,
researchers analyzed the effects of estrogen on 290,827 healthy post-menopausal women from
1982 to 1994. None of the women had a history of cancer or cardiovascular disease when
they enrolled in the study. After 12 years of follow-up, the overall death rate among the
women who took estrogen replacement therapy was 20% lower than among those who did not
take estrogen.
The researchers also found that thin
women who took estrogen at the beginning of the study were 50% less likely to die from
heart disease within 12 years compared with women who never used HRT. However, obese women
did not receive any protection from heart disease from taking estrogen.
Researchers have previously found that
estrogen helps protect women against heart disease. As a woman ages, her risk of heart
disease increases: 9,000 American women under age 45 (before menopause) have heart attacks
each year versus 250,000 women over age 65 (after menopause). Estrogen also appears to
help maintain low cholesterol levels and improve the arteries’ flexibility and
expandability.
According to Dr. Rodriguez, after
menopause, a woman’s fat cells (adipose tissue) are her main source of estrogen.
Since obese women have more adipose tissue, they already have a higher amount of estrogen
than thinner women, and thus the amount of estrogen added with HRT is usually not enough
to have a significant impact against heart disease. This is unfortunate because obese
women are at a higher risk of heart disease than thinner women for reasons unrelated to
estrogen levels, said Dr. Rodriguez in an American Cancer Society news report. Therefore,
obese women may need to consider other options besides HRT to help protect against heart
disease.
A body mass index measures a
person’s total body fat and is derived by multiplying a person's weight in pounds by
703 and then dividing it twice by the person’s height in inches. According to federal
guidelines, women who have BMIs between 25 and 30 are considered overweight and women with
BMIs of over 30 are considered obese.
Besides relieving menopausal symptoms
and helping to protect thin women against heart disease, HRT can also help prevent and
treat osteoporosis, a degenerative bone disease that
affects approximately one half of all women over age 50. However, there has been
controversy over whether or not HRT increases the risk of breast
cancer. According to Dr. Rodriguez, thin women who use HRT may have a higher
risk of breast cancer than obese women because the amount of estrogen added with HRT is
significant for thin women compared with the amount of estrogen added for obese women.
However, in the American Cancer Society
study, which ran from 1982-1994, the researchers did not find an increased risk of death
from breast cancer among the women who took HRT, regardless of their weight. In the study,
the women were likely to receive close monitoring by physicians, increasing the chances
that breast cancer would be detected and successfully treated at an early stage.
Although studies have been
inconsistent, there appears to be an emerging consensus that HRT does not significantly
increase the risk for breast cancer, at least for women who take estrogen less than five
years or who take less than 0.625 mg per day. The Women’s Health Initiative (WHI) is
currently conducting a large study on HRT. The WHI study is a 15-year clinical trial that
is investigating HRT, heart disease, osteoporosis, breast cancer, and colon cancer in
63,000 American women between the ages of 50 and 79. The results of the study will help to
answer many questions about the benefits and risks of HRT. In the meantime, women should
discuss the benefits and risks of taking HRT with their physicians, based on their
individual medical situations.
Additional Resources and References
- The American Cancer Society study
discussed in this article is published in the January 15, 2001 addition of the American
Journal of Epidemiology, http://www.aje.oupjournals.org
- The January 8, 2001 American Cancer
Society News Today report, "Estrogen Protects Heart for Thin Women, Does Not
Increase Cancer Death Rates," is available at http://www2.cancer.org/zine/index.cfm?sc=001&fn=001_01082001_0
- The January 8, 2001 Doctor’s
Guide report, "Estrogen Replacement Lowers Death Rate," is available at http://www.docguide.com/ (free
registration may be required)
- The March 21, 2000 Imaginis.com report,
"Heart Disease in Women More Deadly Than Breast Cancer: Disease Attacks Women
Differently Than Men," is available at http://www.imaginis.com/heart-disease/news/news3.21.00.asp
- To learn more about hormone replacement
therapy (HRT), please visit http://www.imaginis.com/breasthealth/hrt.asp
- To learn more about heart disease,
please visit http://www.imaginis.com/heart-disease/
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